John Adams: Is it, Abby?
Abigail: Well, think of it, John, to be married to the man who is always the first in line to be hanged!
-- from the movie 1776.
In all other respects, John Adams - one of the major players in the ground-breaking uprising that formed the United States of America - was second in line for everything else. To say that this made him a personally bitter man isn't entirely right: he was pretty grumpy and stubborn to begin with.
Adams was one of the major independence leaders in New England... except that he was overshadowed by his more passionate cousin Sam Adams (yeah, the beer guy). He was one of the workers on the Declaration of Independence, the key document in American History and our nation's most sacred secular parchment... except that Thomas Jefferson was the major drafter and provided more of the literary flourish that makes the Declaration so memorable. Adams was one of two major ambassadors to France trying to secure financial aid and military support from France... the other guy was Benjamin Freakin' Franklin, who wooed and wined his way into Frenchmen (and women's) hearts.
And of course, when it came time to vote for our nation's first executive under the Constitution... well, John Adams had to know in his heart that George Washington was the go-to guy there. The only consolation Adams had to have was the knowledge that he'd qualify for President once Washington retired for good.
But by then the American political landscape had shifted: while the Founders attempted to create a non-partisan form of federal government, it couldn't last. People naturally gravitated towards like-minded groups, and quickly two parties formed: The Federalists and the Republican-Democrats (aka the modern Democratic Party). They formed along domestic, foreign, economic, and geographic lines. And they formed around two natural leaders: Democrats (States' rights, France-leaning, agrarian anti-bank) swarmed to Thomas Jefferson; Federalists (Strong central government, British-leaning, business pro-bank) swarmed to... Alexander Hamilton. Once again, Adams was second-place. And while Adams got to be President, Hamilton was used to the idea of being the power-broker behind the scenes (his role during Washington's tenure). This meant Adams and Hamilton - both ambitious men - were quickly at odds.
As a President - as a person - Adams is a textbook example of an Active-Negative. The one word comparative is Compulsive: A-Ns are stubborn and uncompromising, ambitious, hard-working but derive no pleasure or feeling of success, suffers from low self-esteem, and a problem with anger management.
An Active-Negative could be a problem as President - especially on the uncompromising part - but you can agree that at least things get done. A-Ns come in with an agenda or an ideology and gets right to work on it, that quickly defines the administration and the nation. It also creates a ton of political conflict, which shakes up the discourse for both good and ill (sad to say, usually "ill" due to hurt egos and unintended consequences).
Adams' administration was contentious where Washington's more... placid, stable. It didn't help that Adams had decided - out of deference to his predecessor - to keep Washington's second term Cabinet intact. It hampered Adams' abilities to get things done his way because the Cabinet were composed of men who preferred answering to Hamilton, who indulged in behind-the-scenes meddling to Adams' ever-growing ire. And it didn't help that in that age, the Vice President was elected separate from the President: Veeps were the guys who won second place in the Presidential election, which at the time was Thomas Jefferson (this was one of two times in American history the President and Vice President were from different political parties, well three if you count that SOB Tyler). Jefferson was nowhere near interested in helping his ex-friend (they broke their friendship over the French uprising) out against fellow rival Hamilton (the enemy of my enemy... in this case was still an enemy).
Of Adams' administration, there was one dominant matter: how America should respond to the European conflict between Revolutionary France and Great Britain (alongside other fearful monarchies). By the time Adams entered office, the French Revolution had concluded its Reign of Terror and had reverted back to an uneven (and corrupt) Directory coping with wars and inflationary economics. France was winning the ground war but was heating up their foreign adventures at sea, creating issues with the United States trying to ply trade across the Atlantic and Caribbean.
Adams sent diplomatic agents to France to discuss an amicable solution that didn't involve dragging the U.S. into a war it couldn't afford. By 1798 Adams' agents replied back that they were approached by three French officials known only as X Y and Z and told to offer up a huge bribe just to even get one meeting with the French foreign minister Talleyrand. The Americans refused, informed Adams what happened, and two of them returned home. Adams then called on Congress to begin war preparations, but withheld the scandalous letters. When the Democrats in Congress balked, Adams revealed the XYZ Affair to the public. The cry was immediate: "Millions for defense, not one cent for tribute!"
Adams's Active nature kicked into gear. He called on Washington to return and serve as Commander-in-Chief of any organized army Congress would muster (Washington was in no shape to lead: Adams begrudgingly allowed Washington to organize with Hamilton as second-in-command). He formed a new Cabinet post for a Secretary of the Navy (separate from the Secretary of War (Army)) and ordered the first true U.S. naval fleet to be built (the famous ships of the Barbary Pirate Wars and the War of 1812).
But there was also Adams' Negative nature. He knew the United States was still too financially weak to endure a prolonged war against France. He feared getting involved between Great Britain (resolved issues with the Jay Treaty, which was one reason France was angry at the United States) and France would stir up the populus into a civil war of sorts between Anglophile and Francophile. His active nature combined with his negative fears to make another attempt at brokering a deal with France. (Most A-Ns are reluctant to start wars, as they're usually smart enough to know wars don't end well and fearful enough of failing) He re-sent diplomats to France who this time were received warmly by Talleyrand who publicly admitted he had sent the XYZ agents as a form of apology. They were able to hammer out a deal that ended the Quasi-War efforts in the United States.
And this is where Adams' uncompromising A-N habits became his downfall: his resumption of peace talks while the public - especially the Federalists like Hamilton who fancied himself the next great American war hero - were stirred up into war passions caused a break among the Federalist party leaders. They were eager for a war that Adams didn't want. Losing his party leadership would hurt Adams' chances for re-election in 1800.
It didn't help that during the Quasi-War period that Congress passed with a Federalist majority the Alien and Sedition Acts. The nation's first anti-foreigner law that gave government the power to expel unwanted immigrants or travelers to our shores: this was the Federalist response against French emigre agitators. It was also the first censorship law that allowed government to arrest and jail anyone who spoke against the federal government: this was the Federalist response against the Republican-Democratic newspaper publishers railing against Federalist majority rule.
Adams may not have started those Acts but he did sign them into law, and he and the Federalists did profit from them. This is the other big worry about A-N Presidents: they don't like criticism very much. Their uncompromising, angry world-view (best described as "My way or the highway") make them the most likely among Presidents to subvert into dictatorial rule. Other A-Ns during wartime or political strife show the same disregard for dissent (Wilson, Nixon, Cheney).
The Federalists didn't go completely overboard enforcing the Alien Sedition Acts: to be fair, compared to the Reign of Terror and other purges, this was the meekest with only 25 arrests and 10 convictions (Stalin would consider that a coffee break). And there's no evidence that Adams personally oversaw or ordered any persecutions. But like all repressive acts it backfired on Adams and his party: the Republican-Democrats were able to rally against the Acts and make huge wins in the 1800 election. Combined with Adams' losing his party's support, he fell in his re-election bid to his rival Jefferson. Worst of all, the Democratic reaction to the Alien and Sedition Acts were to lay the foundations to two ideas destructive to the concept of federalism: state nullification - when Jefferson and James Madison wrote the Kentucky and Virginia Resolutions - and secession. Even though such arguments have been shot down - nullification in the Peters case, secession through the American Civil War and Texas v. White - we're stuck with the damn things even today...
From David and Robin Whitney's American Presidents (8th ed.), one of the sources I'm using, a final summary:
He tried to do what he believed was right for his country, rather than what was politically expedient. His blunt frankness sometimes lost him friends, but he was respected for his honesty even by his political enemies... (p. 18)
Adams' legacy in the end wasn't much except in one regard and he does get a first: he presided over the first relative peaceful transition of the Presidency from one political party to another. And like some A-Ns, his administration's legacies got the benefit of hindsight showing where his caution about war proved the most sensible.